In prior-art, there are solutions for the measurement of liquid flow in which a liquid channel is provided with a weir or a wall with an orifice in it to permit liquid flow through it. The rise of liquid surface caused by the weir is measured. The liquid level in the weir container is proportional to a mathematical formula of the flow rate or according to a curve obtained via calibration measurements. An apparatus of this type is presented in international patent application publication WO 96/36851. One of the drawbacks of prior-art solutions is that when the height of fall of the liquid is increased, the flow rate increases in front of the weir opening, leading to a lower accuracy of measurement.
The object of the present invention is to achieve an apparatus for the measurement of liquid flow that makes it possible to eliminate the drawbacks of prior art and to achieve a measuring apparatus that is capable of a better accuracy of measurement even in the case of a large height of fall of the liquid.